The present invention relates to air bag manufacturing machines and a method of making sealed air bags.
Plastic bags comprising relatively small pockets containing air are known for use in the packaging industry. The air bags are usually placed between a container and an article to be transported in order that the article is cushioned from the side walls of the container and therefore is unlikely to suffer damage during transportation.
In existing machines that are used for this purpose, a tube of plastics is advanced and then halted in order that an air injector can pierce one layer of the film to the space between the layers. Air is then injected in order to force air into and divert the opposed portions of the tubular plastics. Seals are provided periodically along the length of the plastics in order to define the closed bags and to retain the air between the seals. The seals are applied in the form of two closely spaced apart seals in order that the hole that has been made by the injector piercing the film can be between those seals without air being able to escape from that injection hole.
Air is injected into the tube whilst the plastics is stationary. The plastics is then advanced to a sealing station that applies the two seals. Consequently, there is a loss of air through the injection hole before sealing which loss is difficult to predict. In addition, as the film is stationary during both the injection and during the sealing operations, the production of bag rates is relatively slow.
The air that is injected is provided from a compressor. The provision of such compressors is expensive. Furthermore, they generate a lot of water that has to be drained every night and they require extensive servicing and a significant power consumption.
It is an object of the present invention to attempt to overcome at least one of the above or other disadvantages.
According to one aspect of the present invention an air bag packaging machine comprises stock supply means arranged, in use, to supply a stock of material to be formed into bags to an air supply station arranged, in use, to at least partially fill a space between opposing portions of material to be formed into bags with air and a sealing station arranged, in use, to seal the material to encapsulate air, the machine being characterised in that the air supply station is arranged to move with the stock of material along at least part of the extent of travel of the stock as the air supply station at least partially fills the space.
The air supply station may be located upstream of the sealing station.
The air supply station may include a piercing member arranged, in use, to pierce a layer of material to be formed into bags and to supply air to at least partially fill a space between opposed portions of material through the opening caused by piercing.
The piercing member may be movable relative to the stock of material from a first position in which the piercing member is substantially clear of the material to a second position in which the piercing member has pierced the material.
The present invention may also include driving means arranged, in use, to drive both the stock of material and the air supply station whilst the air supply station is supplying air to at least partially fill the space.
Movement of the air supply member may be arranged to cease before movement of stock from the stock supply station ceases. After cessation of movement of the air supply means the sheet material may be arranged to be conveyed to the sealing station, such as by continuing to move. When the material has been pierced by the piercing member, the portion that has been pierced may be arranged to be located in the region of the sealing station when sealing occurs.
The driving means may comprise linearly movable means such as a linearly movable member arranged, in use, to drive the stock supply means. The linearly movable means may be arranged to cause relative rotation of opposing members between which the stock material is located in order to supply the stock material to the air supply station. The linearly movable means may be reciprocatably movable. Reciprocation of the linearly movable means may be arranged to supply stock in one direction of reciprocal movement with stock remaining stationary during at least part of the other direction of linear movement.
The linearly movable member may include a rack gear with which a tooth member associated with at least one opposing member may be arranged to engage to cause rotation of that tooth member. The machine may include means arranged to cause rotation of at least one opposing member during one direction of rotational movement with rotation not being imparted to the opposing member during the other direction of rotation of the toothed member.
The linearly movable means may be arranged to impart movement to the air supply means during at least part of the movement of the linearly movable member. When the linearly movable member is moving in one direction, the air supply means may be arranged to supply air to a space between opposed portions of the stock during at least part of that movement. The air supply means may be arranged to move with the linearly movable member during at least part of that movement only. The air supply means may be arranged to be driven by the linearly movable means by frictional engagement. The air supply means may be arranged to contact an abutment to prevent movement of the air supply means during part of the movement of the linearly movable means in one direction.
The driving means may be arranged to drive air displacement means that are arranged to supply air to the air supply means. Linear movement of the linearly movable means in at least one direction may be arranged to drive the air displacement means in a linear direction in order to displace air at least part of which is arranged to be supplied to the air supply means.
The sealing station may be arranged to provide at least one and preferably two seals transverse to the direction of movement of the stock from the supply means. The sealing station may be arranged to provide at least two closely spaced seals transverse to the direction of movement of the stock from the stock supply means. Those two closely spaced seals may be arranged to be located either side of an opening in the stock material through which air has been supplied.
The sealing station may be arranged to seal a tubular portion of stock from the stock supply means.
The machine may include air movement means arranged, in use, to force air within and along the stock of material in the direction that the stock of material is arranged to travel. The air movement means may be arranged to move with a part of the sealing station that is arranged to move in order to effect sealing such as by moving at least partially towards the material. The air movement means may include a portion that extends upstream from the sealing station and which is inclined, in the upstream direction, towards the stock. That member may be arranged to move, whilst effecting movement of air, to alter its angle of inclination such that the angle is reduced relative to the stock. The member may be movable against a resilient bias. The air movement means may be arranged to force air past the sealing station prior to sealing being effected.
According to another aspect of the present invention an air bag manufacturing machine comprises stock supply means arranged, in use, to supply a stock of material to be formed into bags to an air supply station arranged in use to at least partially fill a space between opposing portions of material to be formed into bags with air, and a sealing station arranged, in use, to seal the material to encapsulate air within opposed portions of material, the machine being characterised in that it includes air displacement means that is arranged to supply at least part of the air that is supplied to the air supply means with the air displacement means being caused to move with part of the force that is also used to power the stock supply means.
The air displacement means may also be caused to move with a force a part of which is also caused to move the air supply station and/or the stock supply means and/or part of the sealing station arranged to effect the seal.
The air displacement means may be arranged to move in a return direction during at least part of the time when air is not being supplied by the air supply means. The air displacement means may be linearly movable. The air displacement means may be arranged to move with a linearly movable member which, in use, is arranged to power the stock supply means.
The air displacement means may comprise a pneumatic hydraulic cylinder and piston.
According to a further aspect of the present invention an air bag manufacturing machine comprises stock supply means arranged, in use, to supply a stock of material to be formed into bags to an air supply station arranged, in use, to at least partially fill a space between opposing portions of material to be formed into bags with air and a sealing station arranged, in use, to seal the material to encapsulate air in the sealed material, the machine including air movement means arranged, in use, to cause air to flow along the stock and within the stock in the direction of travel of the stock.
The air movement means may comprise a member arranged to cooperate with an outwardly facing surface of the stock of material in order to exert a compressive force on that material. The air movement means may be arranged to apply a greater force to the outer surface of the stock of material at an upstream region than the air movement means applies to a downstream region.
The air movement means may comprise a member that is inclined towards the outwardly facing surface of the stock of material in an upstream direction. The member may be pivotally mounted. The member may be movable. The member may be arranged to alter its angle of inclination when the member is moved down towards the outer surface of the stock of material, for instance against a resilient bias.
The air movement means may be arranged to cause air to move past the sealing station prior to sealing occurring.
According to a further aspect of the present invention a method of forming a sealed air bag comprises moving sheet material to be formed into the bag and supplying air to a space between material to be formed into the bag whilst moving the air supply with the material.
The method may comprise piercing the material in order to cause air to enter a space between opposed portions of the material to at least partially fill the bag and moving the portion that has pierced the bag and is causing air to enter the bag with the material.
The method may comprise ceasing to supply air to at least partially fill a region between opposed portions of the material whilst the material continues to move.
According to another aspect of the present invention a method of making air bags that are substantially sealed comprises supplying air by causing mechanical movement of a part that displaces air with the mechanical movement being caused by mechanical movement of other parts of the machine.
According to a further aspect of the present invention a method of making sealed air bags comprises pushing air that is located between opposed portions of material along the material prior to the material being sealed.
The method may comprise pushing the air past a portion of the material that is to be sealed before sealing that portion.